To keep premium prices down for individuals and small businesses buying coverage through new online marketplaces, insurers have created smaller networks of hospitals. But consumers and policy experts have wondered, just how small?

Based on research he says it took his team weeks to develop, Mango said the majority of the lowest-priced insurance plans sold through the new online marketplaces use very small networks of hospitals. The study did not evaluate doctor participation in those networks.

The issue of whether doctors or hospitals are in a network is often of utmost importance to consumers choosing an insurance policy. But prices also are important.

Mango said his research looked at 20 urban areas representing about 25 percent of the uninsured. To develop a definition of broad or narrow, McKinsey identified the biggest 20 hospitals by their number of beds. Insurance plan networks with 15 or more big hospitals were tagged as broad networks. Those with 7 to 14 were considered narrow, and those with 6 or fewer of the top 20 were considered ultra-narrow.” - Marketplace Plans’ Networks Are Very Small, Study Finds. Kaiser Health News, 12/12/2013